Joseph W. Galvin, DO, FAAOS and Xinning Li, MD
Instability in the pediatric and adolescent athlete is predominantly anterior in direction and secondary to trauma. Posterior and multidirectional instability (MDI) are less commonly involved in this population. With an increase in adolescent participation in contact sports, there has been a resultant rise in pediatric sports injuries.1 Also, single-sport focus and year-round sport participation have likely contributed to the high rate of anterior shoulder instability.2 Studies have shown high recurrence rates following nonoperative treatment of anterior shoulder instability in adolescent skeletally mature athletes.3 Therefore, surgical treatment is indicated in these adolescent athletes to stabilize the shoulder and prevent further damage both to the soft tissue and cartilage due to high rates of recurrent instability. However, in the skeletally immature athlete, those typically younger than 13 years, recent studies have shown lower rates of recurrent instability; therefore, nonoperative treatment is the most appropriate initial management in this population.2,4 Leroux et al2 examined the epidemiology of anterior shoulder instability and found that the rate of closed reduction (primary or recurrent) for the 10- to 13-year age group is considerably lower than for 14- to 16-year-old patients, and therefore these skeletally immature individual should be treated conservatively. These results are similar to the findings of Li et al4 after performing a comprehensive review of the literature on this topic. Furthermore, posterior instability and MDI are becoming increasingly recognized in adolescent populations. The initial treatment for both of these conditions is nonoperative with dedicated physical therapy.
In this chapter we will review epidemiology, natural history of shoulder instability in pediatric and adolescent patients, and indications for nonsurgical and surgical management. Additionally, we will review the special considerations both for arthroscopic and open stabilization of the pediatric and adolescent athlete, surgical techniques, rehabilitation, and outcomes.
There is a high incidence of anterior shoulder instability among young men and boys in the United States. Zacchilli and Owens5 queried the National Electronic Injury Surveillance System, which is composed of a probability sample of all injuries presenting to US emergency departments from 2002 to 2006. A total of 8940 dislocations were identified over this time period with an overall incidence rate of 23.9 dislocations per 100,000 person-years. The maximum incidence rate occurred in individuals between ages 20 and 29 years, with age and male sex identified as risk factors for a dislocation event. Leroux et al2 found that the person-time incidence rate of anterior shoulder instability in 10- to 16-year-olds in Canada between April 2002 and September 2010 was 20.1 dislocations per 100,000 person-years, with the highest incidence rate reported in male patients age 16 years (164.4 dislocations per 100,000 person-years) and lowest incidence rate in female patients age 10 years (1.3 dislocations per 100,000 person-years). The differences in the person-time incidence rates reported are likely secondary to the increase in youth sports participation, particularly contact and collision sports among adolescent male patients.6,7 Furthermore, only 2% of dislocations occurred in patients younger than 10 years.5,8 Postacchini and colleagues9 also found the incidence of shoulder dislocations in patients 13 years or younger to be very rare, with only 3 patients (0.38%) out of 780 patients with anterior shoulder instability treated in their institution in a 4-year time period.
The natural history of anterior shoulder instability and the risk of recurrence are highly variable and are based on age and skeletal maturity. Based on the available literature, skeletally immature individuals, typically those younger than 13 years, have a lower recurrence rate than skeletally mature (age 14 years and older) adolescents. Cordischi et al10 prospectively followed 14 skeletally immature patients (age 10.9 to 13.1 years) who sustained an initial traumatic anterior glenohumeral dislocation and were treated nonoperatively. At final follow-up of mean 5.6 years, 3 (21%) patients sustained a recurrent shoulder dislocation that required surgical stabilization. Similarly, Lampert et al11 conducted a retrospective review of 54 patients (age range, 4 to 18 years) who sustained an anterior shoulder dislocation. Patients younger than 14 years (mean, 11.2 years) had no recurrent instability, whereas those 14 years or older (mean, 15.8 years) had a 69% recurrent dislocation rate. In contrast, other studies have shown higher recurrence rates in skeletally immature patients, ranging from 53% to 100%.12,13 Deitch et al14 performed a retrospective cohort study of 32 patients, age 11 to 18 years, following a traumatic anterior shoulder dislocation. Recurrent instability occurred in 24 of 32 patients (75%). In skeletally immature patients the recurrence rate was 53%, compared to 80% in skeletally mature children.13 Furthermore, in the largest population-based epidemiologic study of anterior shoulder dislocation in patients age 10 to 16 years, Leroux et al2 found a correlation between age and recurrent dislocation requiring a second closed reduction. Of the 2066 patients who required primary closed reduction, the highest rate of recurrence was seen among patients age 16 years (42.3%) and the lowest in patients age 10 to 12 years (17.4%). Postacchini and colleagues9 also reported a similar recurrence (92%) and a mean number of 7 redislocations in patients age 14 to 17 years compared to 33% recurrence with only 1 redislocation in patients age 13 or younger. Despite variable results in the literature regarding recurrent instability, initial management of a first-time dislocation in a skeletally immature patient should be nonsurgical.8
Management of anterior shoulder instability in adolescents with closed physes is entirely different. The published recurrence rate is consistently much higher in this population, which may be related to increased contact or collision sports participation in this age group, and some authors have hypothesized that the differences in anatomy may play a role in the recurrence rate with less elasticity of the anterior inferior glenohumeral ligament in adult patients than in the skeletally immature patient. A recent prospective study evaluated the natural history of nonoperatively treated anterior shoulder dislocations in adolescents with closed physes at a single institution.3 The authors prospectively followed 133 adolescent patients (mean age, 16.3 years; range, 13 to 18) after a first-time anterior glenohumeral dislocation. The majority of patients (102, 76.7%) had a recurrent dislocation. The incidence of recurrent shoulder instability was 59%, 38%, 21%, and 7% at 1-, 2-, 5-, and 10-year follow-up, respectively. This mirrors similar redislocation incidences seen in long-term natural history studies in the adult patient population.15,16
CLINICAL AND RADIOGRAPHIC EVALUATION
It is essential to separate shoulder instability in the adolescent patient population as either atraumatic or traumatic in etiology. Patients with atraumatic onset of shoulder instability will typically present with multidirectional symptoms that will need to be evaluated for ligamentous laxity (Beighton scores), scapular thoracic kinematics, and possible connective tissue disease. Patients with traumatic locked shoulder dislocation often present with an obvious deformity, pain, and limitation in shoulder range of motion. Physical examination including range of motion testing, signs of ligamentous laxity, apprehension/relocation, load and shift, posterior jerk test, and careful neurovascular examination are essential in the initial evaluation of these adolescent athletes. Plain radiographs are the initial imaging obtained if a shoulder dislocation is suspected. Orthogonal views are paramount and typically include anteroposterior view, axillary view, and occasionally scapular-Y view. The axillary view is essential following shoulder reduction to confirm that the humeral head is centered on the glenoid. Although magnetic resonance imaging (MRI) scans are typically not necessary or practical in the acute setting, MRI does provide specific details regarding concomitant soft-tissue injuries following a shoulder dislocation. The status of the labral tissue and presence of an injury (ie, bony or soft-tissue Bankart lesion), as well as whether the patient has an open or closed physis, may affect treatment decision making following a shoulder dislocation (Figures 25-1A and 25-1B). Additionally, in adolescent athletes with recurrent instability and attritional glenoid bone loss, a computed tomography (CT) scan is essential to evaluate the amount of bone loss that may affect surgical indications. Please see the chapter on physical examination and radiographic evaluation for more in-depth details related to each clinical examination finding as well as the key radiographic images for adolescent athletes who present with shoulder instability.
The initial management of shoulder instability in skeletally immature individuals is nonsurgical, as discussed earlier. In the adolescent skeletally mature patient population with a first-time dislocation, the decision on whether to undergo surgery should be established through a shared decision-making process (Figure 25-2). Regardless, most patients are typically treated with a brief period (less than 3 weeks) of immobilization for pain reduction and comfort. However, there is a paucity of evidence to guide decision making on the need for post-reduction immobilization following a first-time anterior shoulder dislocation. Henry and Genung17 studied 121 first-time anterior shoulder dislocators and found that the rate of recurrent instability for those immobilized in a sling post-reduction was 90% vs 85% among those who were not immobilized. Additionally, no studies have found that immobilization for greater than 1 week has any effect on recurrence rate.18
Post-reduction external rotation (ER) immobilization acutely after injury has also been a topic of controversy in the nonoperative management of first-time anterior shoulder dislocators. Initial imaging and cadaveric studies demonstrated anatomic reduction of the anterior inferior labral tear to the glenoid in the externally rotated (ER) position by the muscle belly of the subscapularis, as opposed to the internal rotation (IR) position. An early preliminary study in 2003 by Itoi et al19 demonstrated a lower recurrence rate in patients treated with ER immobilization (ER: 0% vs IR: 30%) at a mean follow up of 1.3 years. However, more recent literature has not shown a significant difference in outcomes when comparing ER to IR immobilization. Paterson and colleagues18 conducted a systematic review and meta-analysis and found no statistically significant difference in recurrent instability between ER and IR immobilization. Similarly, Whelan et al20 performed a meta-analysis of 6 randomized controlled trials and also found no significant difference between arm position (ER vs IR) for post-reduction immobilization. Therefore, the decision for ER immobilization must be made based on a shared decision-making model with patients and their parents, given the increased cost of an ER immobilizer and the potential difficulty with patient compliance in the adolescent patient population.
ROLE OF PHYSICAL THERAPY
In skeletally immature patients, initial treatment should be nonoperative with a physical therapy program. Physical therapy should focus on strengthening and improved proprioceptive control of the dynamic stabilizers of the shoulder, including the rotator cuff and scapulothoracic stabilizers. There is limited evidence to support the role for physical therapy in skeletally immature or mature adolescents. In the college athlete population, Dickens et al21 prospectively followed West Point cadets (mean age, 20.7; SD 1.63 years) who were in-season athletes (skeletally mature) and treated with an accelerated rehabilitation protocol after a first-time shoulder dislocation. In their protocol, no patient was immobilized after the injury and a supervised physical therapy protocol was started the day after the injury. This consisted of regaining shoulder range of motion and rotator cuff strengthening with light weight. Once symmetric range of motion was achieved, then periscapular and resistance exercises were initiated. If the player was asymptomatic with all rehabilitative exercises, had symmetric and full strength, was able to perform sport-specific exercises, and had no pain or limitations, he or she was cleared for sports participation. Although 73% of patients were able to return to sport during the season, only 27% were able to finish the season without recurrent instability. Gaballah et al22 evaluated a 6-week physical therapy rehabilitation protocol consisting of elastic bands and resistive exercise to improve joint strength and shoulder range of motion in 12 patients with acute primary anterior shoulder instability. They found there was no difference in range of motion and strength between the injured side compared to the uninjured contralateral side at final follow-up. However, compliance remains a challenge when recommending an extensive physical therapy protocol and exercise program in this patient population. There is a high prevalence of low adherence to treatment during the adolescent years, which will increase morbidity and contribute to poorer outcomes with nonoperative management. There are many different factors that affect adherence, including developmental stage, emotional state, socioeconomic factors, and family dynamics. It is important to evaluate for adherence to physical therapy on a regular basis in this patient population.23
Numerous studies have evaluated the outcome both of skeletally immature and mature adolescents following surgical treatment. This is a distinctively different population from the older young adult population (age 20 to 35 years). A number of studies have established the results of operative vs nonoperative treatment in this older population.24–27 The results have demonstrated a significant benefit to arthroscopic stabilization in reducing the risk of recurrent instability as compared to nonoperative treatment.
We have summarized the results of studies examining the outcomes and recurrence rates of operative vs nonoperative treatment of anterior shoulder instability in adolescents (Table 25-1) as well as proposed an algorithm both for conservative and surgical management in this patient population (see Figure 25-2). We included studies comparing both nonoperative treatment to arthroscopic and open stabilization procedures for anterior shoulder instability. Gigis et al28 performed a prospective cohort study of adolescent patients (ages 15 to 18 years) after a first-time anterior glenohumeral dislocation. A conservative treatment group (27 patients) and an arthroscopic stabilization group (38 patients) were identified and followed for 36 months. The recurrence rate for the conservative treatment group was 19 of 27 (70.3%), and 5 of 38 (13.1%) for the operative group. The authors concluded that nonoperative treatment of adolescent patients (age 15 to 18 years) resulted in an unacceptably high rate of recurrent instability compared to arthroscopic Bankart repair. Similarly, Jones and colleagues29 performed a retrospective review of adolescent patients (mean age, 15.4 years; range, 11 to 18 years) who underwent arthroscopic Bankart repair, with a mean follow-up of 25.2 months. The authors had an overall 15.6% recurrent instability rate. Furthermore, there is a paucity of literature examining the role of the Latarjet procedure in the management of recurrent anterior shoulder instability in a pediatric population. Khan et al30 conducted a retrospective cohort study of 49 patients who underwent treatment for recurrent anterior shoulder instability at a mean age of 15.9 years (range, 13 to 16 years). All patients had open physes on radiographs at the time of injury. Approximately half the cohort underwent nonoperative treatment and the other half underwent an open Latarjet procedure. The recurrence rate for the nonoperative and operative group was 52% and 7%, respectively. This study further confirmed that with short- to mid-term follow-up, operative treatment of anterior shoulder instability in the adolescent patient results in lower recurrence rates as compared to nonoperative treatment. Additionally, Blackman et al31 reported the results of revision anterior shoulder stabilization surgery in adolescent athletes (ages 14 to 18 years) in a retrospective study. Of the 90 patients undergoing primary shoulder stabilization, 15 (17%) failed and underwent revision stabilization surgery. With an average follow-up of 5.5 years, 5 revision patients (33%) had recurrent instability requiring another revision surgery. Although the authors were unable to identify specific risk factors for failure after revision surgery, they concluded that adolescent patients who fail primary stabilization also have a high failure rate following revision surgery with mid-term follow-up.